// ~~ icebear ~~
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> ii;
typedef pair<int, ii> iii;
template<class T>
bool minimize(T &a, const T &b) {
if (a > b) return a = b, true;
return false;
}
template<class T>
bool maximize(T &a, const T &b) {
if (a < b) return a = b, true;
return false;
}
#define FOR(i,a,b) for(int i=(a); i<=(b); ++i)
#define FORR(i,a,b) for(int i=(a); i>=(b); --i)
#define REP(i, n) for(int i=0; i<(n); ++i)
#define RED(i, n) for(int i=(n)-1; i>=0; --i)
#define MASK(i) (1LL << (i))
#define BIT(S, i) (((S) >> (i)) & 1)
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define all(x) x.begin(), x.end()
#define task "icebear"
const int MOD = 1e9 + 7;
const int inf = 1e9 + 27092008;
const ll INF = 1e18 + 27092008;
const int N = 5000 + 5;
int n, f[N];
vector<int> G[N];
char c[N];
void dfs(int u, int par) {
for(int v : G[u]) if (v != par) {
dfs(v, u);
f[u] += f[v];
}
if (c[u] == '1') {
f[u] = max(f[u] - 1, 1);
if (par == -1)
for(int v : G[u]) maximize(f[u], f[v] + 1);
}
}
void init(void) {
cin >> n;
FOR(i, 2, n) {
int u, v;
cin >> u >> v;
G[u].pb(v);
G[v].pb(u);
}
FOR(i, 1, n) cin >> c[i];
}
void process(void) {
int ans = 0;
FOR(i, 1, n) if (c[i] == '1') {
memset(f, 0, sizeof f);
dfs(i, -1);
maximize(ans, f[i]);
}
cout << ans;
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
if (fopen(task".inp", "r")) {
freopen(task".inp", "r", stdin);
freopen(task".out", "w", stdout);
}
int tc = 1;
// cin >> tc;
while(tc--) {
init();
process();
}
return 0;
}
